Ulnar neuropathy at wrist- Electrophysiological approache
1. Ulnar Neuropathy at wrist
Electrophysiological Approach
Dr.Roopchand.PS
Senior Resident Academic
Department of Neurology.
2. Introduction:
⢠Rare than ulnar neuropathy at elbow.
⢠Can mimic early MND.
⢠Good knowledge of local anatomy required.
3. Anatomy:
⢠Ulnar nerve enters the wrist at Guyons canal.
â Proximally pisiform bone
â Distally hook of hamate
â Floor : transverse carpel ligament, hamate,
triquetrous bone
â Roof loosely formed at inlet and thick band of
tissue at outlet â pisiohamate hiatus.
â At the hiatus divides in to ulnar sensory branch
and deep palmar motor branch.
4.
5.
6. Supply:
1. Hypothenar motor: At hiatus
â ADM, Opponence digiti minimi, flexor digiti
minimi, palmaris brevis.
2. Superficial sensory br:
â Volar 5th and medial 4th digit.
3. Deep palmar motor br:
â 3rd and 4th lumbricals, four dorsal and three
palmar interossei, adductor pollicis, flexor pollicis
brevis deep head.
7. Clinical:
⢠Can be typed according to location of lesion
and fibers affected.
â Distal deep palmar motor lesion.
â Proximal deep palmar motor lesion.
â Proximal canal lesion.
â Pure sensory lesion (rare).
Most common
8.
9. Presentation:
⢠Weakness and atrophy of ulnar intrinsic
muscle.
⢠Thenar and hypothenar wasting can be seen
⢠Benediction hand posture, Formentâs sing,
Wartenbergâs sign can be seen.
⢠Sensory disturbance over volar 5th and medial
4th finger.
â Dorsal medial aspect spared.
16. Ulnar motor study recording FDI:
⢠Distal deep palmar br
lesion:
â Latency and CMAP
amplitude affected.
â When compared with
ADM latency â highly s/o
UNW
â ADM recordings also
affected in more
proximal lesions
⢠>2ms difference
significant..
18. Median Second lumbrical VS Ulnar Int
DML:
⢠Same as Median study
in CTS.
⢠Latency diff > 0.4
significant.
⢠If there is associated
CTS â difficult to
interpret.
19. Wrist and Palm stimulation:
⢠FDI recorded.
⢠Stimulated 3cm above
the wrist and 4cm distal
to distal palmar crease.
⢠Drop in amplitude or
decrease in CV.
⢠Any CV <37m/s is of
localizing value.
20. Short segment Incremental studies.
⢠Inching done from 2 to
4 cm above and 4 to 6
cm below distal wrist
crease.
⢠1 cm intervals.
⢠NL 0.1 to 0.3 ms/cm
⢠Latency >0.5ms â focal
slowing.
21. ⢠Wrist and palm stimulation showing focal
slowing 100% specific.
⢠Inching is also very sensitive and specific.
⢠In lumbrical-interossei study increasing the cut
off value to 0.7 can eliminate the problem of
co existent median neuropathy.
⢠FDI vs ADM latency comparison is least
sensitive.
22. EMG approach:
⢠FDI and ADM sampled to look for
distal/proximal deep br involvement.
⢠FDP5 and FCU : to r/o ulnar neuropathy
proximal to wrist.
⢠Radial and Median innervated C8 muscles &
lower cervical paraspinal muscles: to r/o
radiculopathy.
â Abd. Pollicis brevis, flex. Pollicis longus, ext.
indices proprius.